Phenotype and genotype predictors of BMI variability among European adults

Weight fluctuation, mortality, and cardiovascular disease in adults in 18 years of follow-up: Tehran Lipid and Glucose Study

PURPOSE

Controversies exist in the effect of body weight loss and fluctuation on cardiovascular disease (CVD) and mortality. This study aims to assess the effect of weight variability on CVD and all-cause and cardiovascular mortality in the Tehran Lipid and Glucose Study (TLGS) cohort.

METHOD

Participants aged  ≥ 40 year at the baseline period with at least 3 BMI measurements were included in this study. After excluding individuals with cancer, CVD, end-stage renal disease, systemic use of glucocorticoids, pregnancy, and missing covariates at the baseline, a total of 3461 participants were enrolled and followed for 18 years. BMI variability was defined using root mean squared error (RMSE) and average successive variability (ASV). In the RMSE method, BMI variability was calculated using the best-fitting model for BMI trend of each subject. Multivariate Cox proportional hazard models were applied to assess BMI variability's effect on CVD and mortality.

RESULTS

Among the 3461 participants in this study, the group with the highest weight variability had an increased risk of death for all-cause (HR 1.65; 95% CI 1.21-2.25), non-cardiovascular (HR 1.77; 95% CI 1.24-2.53), and non-cancer (HR 1.77; 95% CI 1.25-2.50) mortality. However, BMI variability showed to be protective against CVD (HR 0.76; 95% CI 0.6-0.97). These findings were significant in males, non-smokers, participants with age  ≤ 60 year, BMI < 30, negative BMI slope, and both diabetic and non-diabetic subjects.

CONCLUSION

High BMI variability is associated with increased risk of all-cause, non-CVD, and non-cancer mortality, although protective for the CVD event. Appropriate strategies for body weight maintenance after weight loss could be adopted to avoid weight variability, particularly in non-obese subjects.

Stability in BMI over time is associated with a better cognitive trajectory in older adults

OBJECTIVE

Evidence on simultaneous changes in body mass index (BMI) and cognitive decline, which better reflect the natural course of both health phenomena, is limited.

METHODS

We capitalized on longitudinal data from 15,977 initially non-demented elderly from the Alzheimer's Disease Centers followed for 5 years on average. Changes in BMI were defined as (1) last minus first BMI, (2) mean of all follow-up BMIs minus first BMI, and (3) standard deviation of BMI change from baseline and all follow-up visits (representing variability).

RESULTS

Participants with significant changes in BMI (increase or decrease of ≥5%), or who had greater variability in BMI, had faster cognitive decline. This pattern was consistent irrespective of normal (BMI < 25; N = 5747), overweight (25 ≤ BMI < 30; N = 6302), or obese (BMI ≥ 30; N = 3928) BMI at baseline.

CONCLUSIONS

Stability in BMI predicts better cognitive trajectories suggesting clinical value in tracking BMI change, which is simple to measure, and may point to individuals whose cognition is declining.

BMI variability and incident diabetes mellitus, Tehran Lipid and Glucose Study (TLGS)

Previous epidemiologic studies debated the association of body mass index (BMI) trends with cardiovascular disease and mortality. This study aimed to evaluate the association of BMI variability and slope with the incidence of Type 2 diabetes mellitus (T2DM) in a sex-stratified 15.8-year follow-up in the population-based Tehran Lipid and Glucose Study (TLGS). Of 10,911 individuals aged 20-60 years, 4981 subjects were included and followed for 15.8-years. The slope coefficient of BMI in the linear regression model represented individuals' BMI trends up to the incidence of DM. The root mean squared error (RMSE) of the BMI linear trend was selected to reflect BMI variability through six follow-ups. Cox proportional hazards regression was used to investigate the association of the baseline BMI, BMI slope and RMSE with the incidence of T2DM among men and women. Multivariable-adjusted HRs of T2DM for each SD increment in BMI slope was 1.18 (95% CI: 0.94-1.48, p = 0.161) in normal weight men and 1.26 (95% CI: 1.10-1.44, p = 0.001) in overweight and obese men. However, in women, each SD increment in BMI slope increased the risk of T2DM with a HR of 1.19 (95% CI: 1.01-1.40, p = 0.039) in normal weight, and 1.14 (95% CI: 1.08-1.19, p < 0.001) in women with BMI ≥ 25 kg/m². In men with a baseline BMI ≥ 25 kg/m², BMI-RMSE was associated with a decreased risk of T2DM (HR: 0.71, 95% CI: 0.53-0.93, p = 0.015). Baseline BMI was not associated with the risk of diabetes in men and women. Positive BMI slope is associated with the development of diabetes in both sexes. The association of BMI variability with incident T2DM differs according to sex and baseline BMI. BMI variability is associated with a lower risk of T2DM in overweight and obese men. BMI variability in women and baseline BMI in both gender are not related to the risk of T2DM.

Predictive Utility of Alternate Measures of Physical Activity and Diet for Overweight and Obesity in Low-Income Minority Women

PURPOSE

The purpose is to compare the predictive utility of alternate measures of diet and physical activity for overweight and obesity among low-income minority women.

DESIGN

Cross-sectional analysis of baseline data from a cohort study.

SETTING

Three public housing developments in South Los Angeles.Subjects: Adult women (N = 425).

MEASURES

Primary outcome-weight status (normal BMI, overweight, or obese). Primary predictors- diet: 24-hour dietary recalls (Healthy Eating Index), dietary screener (intake of specific food groups), and single-item survey question (diet quality); physical activity: accelerometry (minutes/day of moderate-to-vigorous activity), short recall questionnaire (minutes/week of moderate and vigorous activity), and single-item questions (days per week did exercise; self-assessment of overall activity level).

ANALYSIS

Multinomial logistic regression models, controlling for socio-demographic covariates. Models are built up starting with least resource-intensive measures of diet and physical activity (single items) and sequentially adding more resource-intensive measures. Model performance is assessed via information-based model selection indices.

RESULTS

Adjusted relative risk for obesity for single-item measures ranged from .61 to .64 for diet (P < .01) and from .80 to .81 for physical activity (P <.05). The added value of resource-intensive measures was negligible for physical activity and at best small for diet.

CONCLUSION

Single-item questions for diet and physical activity can provide valuable information about risk for overweight and obesity in low-income minority women when more resource-intensive assessments are infeasible.

Repercussions of absolute and time-rated BMI "yo-yo" fluctuations on cardiovascular stress-related morbidities within the vascular-metabolic CUN cohort

AIMS

The association between body mass index (BMI) fluctuation and BMI fluctuation rate with cardiovascular stress morbidities in a Caucasian European cohort was evaluated to ascertain the impact of weight cycling.

METHODS

A total of 4,312 patients of the Vascular-Metabolic CUN cohort (VMCUN cohort) were examined and followed up during 9.35 years ( ± 4.39). Cox proportional hazard ratio analyses were performed to assess the risk of developing cardiovascular stress-related diseases (CVDs) across quartiles of BMI fluctuation, measured as the average successive variability (ASV) (ASV = |BMIt0 - BMIt1| + |BMIt1 - BMIt2| + |BMIt2-BMIt3| +…+ |BMItn - 1 - BMItn|/n - 1), and quartiles of BMI fluctuation rate (ASV/year).

RESULTS

There were 436 incident cases of CVD-associated events involving 40,323.32 person-years of follow-up. A progressively increased risk of CVD in subjects with greater ASV levels was found. Also, a higher level of ASV/year was significantly associated with an increased risk of developing CVD stress independent of confounding factors with a value of 3.71 (95% CI: 2.71-5.07) for those in the highest quartile and 1.82 (95% CI: 1.33-2.50) for those in the third quartile.

CONCLUSIONS

The BMI fluctuation rate seems to be a better predictor than BMI fluctuation of the potential development of cardiovascular stress morbidities. The time-rated weight fluctuations are apparently more determinant in increasing the risk of a CVD than the weight fluctuation itself, which is remarkable in subjects under "yo-yo" weight patterns for precision medicine.

Genetic polymorphisms associated with obesity in the Arab world: a systematic review

BACKGROUND

Obesity, one of the most common chronic health conditions worldwide, is a multifactorial disease caused by complex genetic and environmental interactions. Several association studies have revealed a considerable number of candidate loci for obesity; however, the genotype-phenotype correlations remain unclear. To date, no comprehensive systematic review has been conducted to investigate the genetic risk factors for obesity among Arabs.

OBJECTIVES

This study aimed to systematically review the genetic polymorphisms that are significantly associated with obesity in Arabs.

METHODS

We searched four literature databases (PubMed, Science Direct, Scopus, and Google Scholar) from inception until May 2020 to obtain all reported genetic data related to obesity in Arab populations. Quality assessment and data extraction were performed individually by three investigators.

RESULTS

In total, 59 studies comprising a total of 15,488 cases and 9,760 controls were included in the systematic review. A total of 76 variants located within or near 49 genes were reported to be significantly associated with obesity. Among the 76 variants, two were described as unique to Arabs, as they have not been previously reported in other populations, and 19 were reported to be distinctively associated with obesity in Arabs but not in non-Arab populations.

CONCLUSIONS

There appears to be a unique genetic and clinical susceptibility profile of obesity in Arab patients.

PPARGC1A gene polymorphism is associated with exercise-induced fat loss

Obesity is a widespread problem within modern society, serving to increase the risk of cardiovascular, metabolic, and neurodegenerative disorders. Peroxisome proliferator-activated receptor gamma (PPARγ) and PPARγ coactivator 1 α (PGC1α) play a key role in the regulation of cellular energy metabolism and is implicated in the pathology of these diseases. This study examined the association between polymorphisms of the PPARG and PPARGC1A genes and individual variability in weight loss in response to physical activity intervention. 39 obese Ukrainian women (44.4 ± 7.5 years, BMI > 30.0 kg/m²) undertook a 3-month fitness program whilst following a hypocaloric diet (~ 1500 cal). Anthropometric and biochemical measurements took place before and after the program. Single nucleotide polymorphisms within or near PPARG (n = 94) and PPARGC1A (n = 138) were identified and expression of PPARG mRNA was measured via reverse transcription and amplification. The association between DNA polymorphisms and exercise-induced weight loss, initial body mass, biochemistry and PPARG expression was determined using one-way analysis of variance (ANOVA). The present intervention induced significant fat loss in all participants (total fat: 40.3 ± 5.3 vs 36.4 ± 5.7%; P < 0.00001). Only one polymorphism (rs17650401 C/T) within the PPARGC1A gene was found to be associated with fat loss efficiency after correction for multiple testing, with T allele carriers showing the greatest reduction in body fat percentage (2.5-fold; P = 0.00013) compared to non-carriers. PPARGC1A (rs17650401) is associated with fat loss efficiency of the fitness program in obese women. Further studies are warranted to test whether this variation is associated with fat oxidation.

Applicability of Obesity-Related SNPs and their Effect Size Measures Defined on Populations with European Ancestry for Genetic Risk Estimation among Roma

Investigations on the impact of genetic factors on the development of obesity have been limited regarding the Roma population—the largest and most vulnerable ethnic minority in Europe of Asian origin. Genetic variants identified from genetic association studies are primarily from European populations. With that in mind, we investigated the applicability of data on selected obesity-related single nucleotide polymorphisms (SNPs), obtained from the Hungarian general (HG) population of European origin, on the Hungarian Roma (HR) population. Twenty preselected SNPs in susceptible alleles, known to be significantly associated with obesity-related phenotypes, were used to estimate the effect of these SNPs on body mass index (BMI) and waist circumference (WC) in HG (N = 1783) and HR (N = 1225) populations. Single SNP associations were tested using linear and logistic regression models, adjusted for known covariates. Out of 20 SNPs, four located in FTO (rs1121980, rs1558902, rs9939609, and rs9941349) showed strong association with BMI and WC as continuous variables in both samples. Computations based on Adult Treatment Panel III (ATPIII) and the International Diabetes Federation’s (IDF) European and Asian criteria showed rs9941349 in FTO to be associated only with WC among both populations, and two SNPs (rs2867125, rs6548238) in TMEM18 associated with WC only in HG population. A substantial difference (both in direction and effect size) was observed only in the case of rs1801282 in PPARγ on WC as a continuous outcome. Findings suggest that genetic risk scores based on counting SNPs with relatively high effect sizes, defined based on populations with European ancestry, can sufficiently allow estimation of genetic susceptibility for Roma. Further studies are needed to clarify the role of SNP(s) with protective effect(s).